The present invention relates to a magnetic thin-film head of layer-wise construction on a nonmagnetic substrate for a recording medium which contains a magnetizable storage layer, into which information can be written along a track by perpendicular (vertical) magnetization. This magnetic head comprises a magnetic conduction body which carries the magnetic flux and of which the end pieces of its magnetic legs, facing the recording medium and which form a main and an auxiliary pole are arranged side by side with predetermined spacing on one flat side of the substrate, the normal of which is oriented at least approximately parallel to the longitudinal direction of the track, and is provided with at least one write/read coil winding, the conducting turns of which extend through a space formed between the magnetic legs.
Such a magnetic head is known, for instance, from European Patent Application No. 0,146,003 A1.
The principle of vertical magnetization for storing information is generally known (see, for instance, "IEEE Transactions on Magnetics", Vol. MAG-16 No. 1, January 1980, pages 71 to 76, or the mentioned European Patent Application).
For this principle, which is frequently also called vertical magnetization, special write/read magnetic heads are required. A head suitable therefor comprises generally, for conducting the magnetic flux, a conducting body {applied to a flat, non-magnetic substrate} of magnetizable material of, in particular, ring-head-like shape which is {-}. Such a magnetic conduction body can comprise, for instance, two magnet legs which are facing the recording medium, wherein one of these forms a main pole, by which a sufficiently strong vertical magnetic field for reversing the magnetization of the storage layer can be generated. The necessary magnetic return can then be accomplished by means of another magnet leg which forms, in particular, a so-called auxiliary pole.
In magnetic heads of this head type, the auxiliary pole is to serve only as the magnetic flux return. Possible cross writing of this auxiliary pole may even by tolerated since the writing main pole can be arranged so that it later overwrites information which may have been written by the auxiliary pole. However, to prevent concurrent reading of the auxiliary pole with its trailing edge at least to a large extent, the spacing formed between the two poles would have to be relatively large so as to assure a far-reaching reduction of the magnetic flux density at the auxiliary pole. In magnetic heads with magnetic poles which are arranged one behind the other as seen in the direction of motion of the head, a gap layer filling this spacing is extremely difficult to make, particularly in thin-film technology.
For this reason, the two poles of the magnet leg shown in the European Patent Application mentioned at the outset, are not arranged in the direction of motion one behind the other, but side by side. Therefore the two magnet legs as well as the turns of at least one write/read coil winding can be applied relatively simply to the non-magnetic substrate body by a thin-film technique. Such techniques are generally known (see for instance, "Feinwerktechnik und Messtechnik", Vol. 88, No. 2, March 1980, pages 53 to 59, or "Siemens-Zeitschrift", Vol. 52, No. 7, 1978, pages 434 to 437). Here, the two poles can also be arranged relatively far from each other, so that optionally, even the formation of separate gap layers between the poles can be dispensed with.
The magnetic conduction body of the magnetic head known from the European Patent Application comprises, besides the two magnetic legs oriented substantially perpendicularly to the recording medium with the main and the auxiliary pole, a further connecting leg extending transversely thereto. This connecting leg which serves as the magnetic return between the two magnet legs should comprise a magnetic material, the easy magnetization of which is aligned substantially perpendicularly with the easy magnetization in the magnet legs. The formation of a corresponding magnetic conduction body, however, is relatively expensive.
In addition, the conductor turns of the write/read coil winding are to extend outside of the relatively extensive auxiliary pole only around the connection zone which is formed between the connecting leg and the magnet leg of the main pole. Such an arrangement, however, requires a corresponding width of the magnetic conduction body and the flat side containing the coil widing of a substrate. The substrate is part of a so-called aerodynamic body (flying body), on the underside of which, facing the recording medium, at least one flying runner is formed. The end face of this flying runner then represents the flat side available for receiving the magnetic head. If now, in a solid disc memory, the flight altitude of the magnetic body above the recording medium is to be kept extremely small and is to be, in particular, less than 0.3 .mu.m, the width of the flying runner is limited to a few 100 .mu.m, for instance, to less than 600 .mu.m, for aerodynamic reasons (see also FIG. 1). Then, however, a design according to the magnetic head known from the European Patent Application can be realized only with difficulty on a flat side of such small width.